CaltechAUTHORS: Monograph
https://feeds.library.caltech.edu/people/García-Javier-A/monograph.rss
A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenThu, 13 Jun 2024 19:27:40 -0700Breaking the limit: Super-Eddington accretion onto black holes and neutron stars
https://resolver.caltech.edu/CaltechAUTHORS:20190617-141021193
Year: 2019
DOI: 10.48550/arXiv.1903.06844
With the recent discoveries of massive and highly luminous quasars at high redshifts (z∼7; e.g. Mortlock et al. 2011), the question of how black holes (BHs) grow in the early Universe has been cast in a new light. In order to grow BHs with M_(BH) > 10^9 M⊙ by less than a billion years after the Big Bang, mass accretion onto the low-mass seed BHs needs to have been very rapid (Volonteri & Rees, 2005). Indeed, for any stellar remnant seed, the rate required would need to exceed the Eddington limit. This is the point at which the outward force produced by radiation pressure is equal to the gravitational attraction experienced by the in-falling matter. In principle, this implies that there is a maximum luminosity an object of mass M can emit; assuming spherical accretion and that the opacity is dominated by Thompson scattering, this Eddington luminosity is L_E = 1.38×10^(38)(M/M⊙) erg s^(−1). In reality, it is known that this limit can be violated, due to non-spherical geometry or various kinds of instabilities. Nevertheless, the Eddington limit remains an important reference point, and many of the details of how accretion proceeds above this limit remain unclear. Understanding how this so-called super-Eddington accretion occurs is of clear cosmological importance, since it potentially governs the growth of the first supermassive black holes (SMBHs) and the impact this growth would have had on their host galaxies ('feedback') and the epoch of reionization, as well as improving our understanding of accretion physics more generally.https://resolver.caltech.edu/CaltechAUTHORS:20190617-141021193Probing the Black Hole Engine with Measurements of the Relativistic X-ray Reflection Component
https://resolver.caltech.edu/CaltechAUTHORS:20190619-103025261
Year: 2019
DOI: 10.48550/arXiv.1903.07130
Over the last decades X-ray spectroscopy has proven to be a powerful tool for the estimation of black hole spin and several other key parameters in dozens of AGN and black hole X-ray binaries. In this White Paper, we discuss the observational and theoretical challenges expected in the exploration, discovery, and study of astrophysical black holes in the next decade. We focus on the case of accreting black holes and their electromagnetic signatures, with particular emphasis on the measurement of the relativistic reflection component in their X-ray spectra.https://resolver.caltech.edu/CaltechAUTHORS:20190619-103025261